If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

neodymium magnets and glue

09-30-2011, 06:08 PM

Like Frank Ford, I love these magnets, especially the 1"x1/8" round. The two times I've glued them they create a white foam that dries very hard.
1. Aluminum was the metal I used
2. and a plastic flashlight

I would glue each piece with some gorilla glue:

the outcome is that the bond seems reduced, because the mags will come loose within a short period of time.

Comment

You might want to try a piece of scrim cloth in-between. Your surfaces probably have very little imperfections and squeezing out the majority of your glue. The cloth will give some stand off and not squeeze it all out and allow the bond.

Comment

Gorilla glue is a urethane glue and the foaming in normal. It's good for some things, especially flexible items but otherwise I don't like the foaming action. Your best bet is epoxy intended for metal. As said, the plating is the weakest part of the bond. The plating is to prevent oxidation of the magnet material. You can sand off the plating and bond directly to the magnet for a much better bond. As long as the magnet isn't exposed to the air it will be fine.

Be careful when sanding. Do it by hand. The magnet alloy is very combustible, much like Misch metal (lighter flints).

Comment

Some kind of non-brittle epoxy would probably be one of the best answers. Cleaning off any oils, etc is going to make a difference. I use brake clean myself, and tissue paper to wipe it all clean without touching fingers to the surfaces being glued.

Of interest to me would be the different expansion ratios of the two parts. I don't know how aluminum compares to the magnet material, but I can imagine that it would have a higher expansion ratio. Flexible epoxy might be the best bet, although some compounds are much better on aluminum than others. PC-7 has worked well for me on al.

Gluing a magnet- I would also tend to make sure the glue forms around the edge of the magnet besides being between the magnet and the surface it's being glued to. I'm still talking epoxy- it should form a bit of a concave bead around the magnet as it flows up the edge.

Here's something I haven't done yet, though thought of it many times. For the best chance at keeping the magnet in place, form a circle of fiberglass cloth over the magnet and down onto the surface. Wet it all out well with the epoxy, and maybe use a short length of pvc pipe to form the cloth down over the magnet while the epoxy cures. If you do a neat job of cutting and placing the cloth, there won't be much to clean up afterwards- maybe a bit of excess epoxy before it starts to gel.

I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my pass​ion-

Comment

This isn't the answer for the op but while on the topic of gluing I'll toss it out there.

I once glued a nickel to a zippo lighter that stayed for 10 years or so. I prepped it with alcohol and used a rubbery brown stick sold in fishing supply places for repairing your waders from leaks. It was called "Magic Patch" and was applied with a match and melted on. It never got brittle and always stayed just a tad rubbery.

I'm just say'en.......

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

It is true, there is nothing free about freedom, don't be so quick to give it away.

Comment

Gorilla glue is a urethane glue and the foaming in normal. It's good for some things, especially flexible items but otherwise I don't like the foaming action.

The problem with this type of glue is that you must have a very close fit between the parts since the foam has very little strength. Any gaps will be filled by foam and the bond will be far less than if the parts fit tightly.

Comment

I just drill a slightly oversize hole and use a special metal glue called loctite. I too made up some holders like Frank Ford does out of brass. In retrospect I'll probably use Aluminum as the brass chips I was picking out of my hair all night